The present embodiments relate to designing a circuit suitable for generating random bits and to a circuit for generating random bits.
In security-relevant applications (e.g., in the case of asymmetric authentication methods), random bit strings are to be provided as binary random numbers. In this case, the lowest hardware complexity possible may be pursued (e.g., it in the case of mobile applications). Known measures for generating random numbers use analog random sources.
As analog random sources, noise sources, such as, for example, the noise from zener diodes, are amplified and digitized. In this case, digital and analog circuitry are combined.
In addition, ring oscillators and variations thereof are used as random number generators. In the case of ring oscillators, which are constructed from an uneven number of inverters connected in series, random jitter, for example, arises from fluctuating propagation times for the signals through the inverters. This jitter (e.g., an irregular fluctuation over time in state changes for the signals sent through the inverters) may be accumulated when there are multiple passes through the ring oscillator circuit, so that ultimately a random analog signal is produced.